Apparatus and process for production of filaments



April 23, 1968 L. HARTMANN ET AL 3,379,811

APPARATUS AND PROCESS FOR PRODUCTION OF FILAMENTS Filed Feb. 3, 1965 Illl :Iluplllnll I, .Il Y

I FIG. B.

INVENTORS LUDWIG HARTMANN WALTER RIEQMULLER GERHARD MULLER ATTORNEYS.

3,379,811 APPARATUS AND PRGCESS FR PRODUCTIQN F FlLAP/IENTS LudwigHartmann, berilockenbach, Walter Riedmiiller,

Heppenheim, and Gerhard Mller, Morlenhach, Germany, assignors to CarlFreudenberg, Weinheim an der Bergstrasse, Germany, a corporation ofGermany Filed Feb. 3, 1965, Ser. No. 430,092 Claims priority,application Germany, Feb. 22, 1964, F 42,095 9 Claims. till. 26d- 210)ABSTRACT 0F THE DSCLOSURE Filament-spinninf7 apparatus and processincluding a substantially coplanar row of spinning orifices adapted tospin a substantially coplanar row of filaments therethrough and means oneach side of the row of orifices and filaments for impinging a fluid,preferably air, onto the filaments as spun, whereby to draw thefilaments wherein the impinging air emerges from slits. Means areprovided for rendering the air emerging from the slits, bothnon-turbulent and substantially uniform in velocity from one end of theslit to the other. These means include two successive channels connectedto each other through conduit means with one of the channels beingconnected to each slit with the air being introduced into the channelfurthest from the slit in order to permit the air to pass through bothchannels, the conduit means therebetween and the conduit means betweenone channel and the slit disn charge opening in such manner as to emergesubstantially non-turbulent and with substantially uniform velocity.

The present invention relates to the production of filaments. Moreparticularly, the invention is concerned with the production offilaments direct from a melt of the material composing the filaments.

In the usual manner of producing textile products, the filaments areformed in for example, a spinning process and are collected on spools.Then the textile product is formed by the working of filaments withdrawnfrom the spools. Several attempts have been made to provide a procedurewherein the textile products are formed concurrently with the productionof the filaments, so that the step of collecting the fibers on spools iseliminated. in particular, attempts have been made to produce non-wovenfabrics in this manner. Thus, polymer melts have been sprayed from aspray gun onto a form provided. for the r production of a fabric. Theresulting products are in general not satisfactory since the filamentsare of low strength. Such filaments do not have a molecular orientationas is desired for the fibers. It has also been proposed to subjectfilament forms issuing from various discharge devices to the influenceof electrical forces so that the filaments are changed to cobweb-likestructures- The cobweb is then collected on a suitable form. Theseproducts do not have as high a strength as is desired.

in the previous attempts to form fabrics direct from a melt, describedabove, the melt outlet openings have been of l mm. diameter, which iscustomary for melt spinning processes. It has also been proposed toutilize smaller outet openings and to direct air currents along the pathof the melt streams issuing from the outlet openings. Electrical forcescan also be utilized. The filaments are then col- 6 lected on a suitableform for the desired fabric. In these prior art attempts, diftlc lty isencountered in the respect that as the width 0f the fabric is increased,the distribution and structure of the fabric tend to become non-uniform.The number of discharge devices is increased in order to increase thewidth and the various forces existing during production of the fieecesinter-act so that ted States Patent O 3,379,3ll Patented Apr'. 23, 1968ICC non-uniformity results in the product. These fabrics have thefurther disadvantage that the filaments thereof do not have desiredmolecular orientation.

Still another procedure for the `production of nonwoven fabrics directfrom a melt is the subject of US. application Ser. No. 341,489, filedIan. 27, 1964 and assigned to the assignee of the present application.ln the process of that application, a spinning head is used which has aplurality of melt outlet openings disposed at spaced intervals along astraight line of any suitable length, for eX- arnple a length equal tothe desired width of the fabric being produced. Melt is discharged fromthe melt outlet openings, and simultaneously air streams generallyparallel to the plane along which the melt streams move, are directedinto impinging relation with the melt streams. The air streams and themelt streams enter a guide passageway which is a channel open at bothends and serves to define the path of travel of the laments as they movefrom the spinneret head to the form on which they are collected. The gasstream also passes through the guide passageway.

The melt streams re drawn by the gas stream into filaments and the gasstream then serves to cool the filaments to the desired extent, prior tocollection thereof as a fleece. This procedure provides the desiredmolecular orientation, and, further, is suitable for production ofiieeccs of substantial width. This procedure, however, as practicedheretofore involves difficulty due to turbulence of the gas streamswhich results in a measure of non-uniformity. This is particularlysignificant in respect to the production of thin fieeces. The turbulenceis due, at least in part, to the structure of the spinning devices used.The conditions of temperature and pressure require supporting membersfor the spinning devices which are in the path of the gas streams, andthus cause turbulence.

It is the principal object of the instant invention to obviate thedisadvantages mentioned for the spinning devices just described.

The manner in which this and other objects are attained, will be bestunderstood by reference to the following description, taken in referenceto the accompanying drawings, wherein:

FlG. l is a cross-sectional view of the back member of the spinnerethead shown in FIG. 2;

FIG. 2 is a cross-sectional View of a spinneret head according to theinvention;

FiG. 2a is an enlarged view of a portion of the spinneret head shown inFIG. 2; and

FlG. 3 is a perspective view of a spinneret head according to theinvention and a guide passageway, and also indicates the path of meltstreams from the spinneret head.

According to the invention, the spinning device is suitable lforspinning a plurality of filaments from a melt by discharging a likenumber of Streams of the melt and drawing the streams into the filamentswith a fluid, preferably a gas and commonly air or stream or air andsteam. The head includes means dening a plurality of melt outletopenings for discharging the streams from the melt, and includes twoslot discharge openings disposed opposite each other across the meltoutlets for delivery of the gas to impinging relation with the meltstreams to draw the streams into the filaments. The invention ischaracterized in that the gas is delivered to the melt streams in amanner that low turbulence exists. The spinneret head is provided withmeans for delivering the gas to the slot discharge openings, andreducing turbulence of the gas. Thus, the head can include an elongateddistribution chamber ttor each slot discharge, which extends over thelength of the slot discharge and is adapted for receiving the air fordelivery to the slot discharge openings, and a passageway whichcommunicates each o-f the distribution chambers with its slot dischargeopening. The passageways have means for reducing turbulence of the fluidpassed therethrough -to the slot discharge openings. Desirably, thepassageways include directional changes and changes in cross-section. Inone construction for the spinneret head, found `well suited for thepurposes of the invention, each of the passageways includes a lengthadjacent its discharge opening and terminating thereat, which divergestowards its slot discharge opening, and each of the passageways has arestriction therein on the distribution chamber side of the diverginglength thereof, ifor reducing pressure of the iiuid flowing through thepassageway. The head is constructed lsuch that the flow paths throughthe two distribution chambers and the passageways is the same. Further,the device of the invention includes an elongated filament guidepassageway for receiving the filament material issuing from the meltoutlet openings and guiding it on to the form on which the textileproduct is produced. The guide passageway is open at both ends and isdisposed in spaced relation with respect to the melt outlet openings. Itreceives the melt streams and also the gas brought into impingingrelation with the melt streams.

Referring to the drawings, as is shown in FIG. 2, a spinneret headincludes a back member a, and a iront member a. The back member is showndisassembled `from the spinneret head in FiG. 1.

The back member a can be milled from a steel plate and includes acone-shaped nozzle b which extends over the length of the head (see FIG.3), and is provided along the apex thereof, at spaced intervals, withmelt outlet openings m. The angle of the cone-shaped nozzle can be aboutl-45, and the apex of the cone can be cut away about 1.0-3 mm. from theapex, to provide a nozzle discharge edge p of about 1.4-2 mm, height.The melt outlet openings m can be spaced 1.0- mm., center to center, andpreferably they are spaced about 2 mm. The diameter of the melt outletopenings m can be 0.1-0.6 mm., and the melt openings are disposed alonga straight line. The openings are -disposed at mid-points along theheight of the edge p. The back member has a bore q leading to the meltdischarge openings m. Further, the back member is milled to provide thechannels e and d, as to which more will be said shortly.

The -txront member a is rformed of two like elements r and s, positionedone on either side of the cone-shaped nozzle b. The rear side of elementr and element s of the front member a' is each milled to provide achannel z, which, when the front member and the back member areassembled, opens into one of the channels e of the back member so thattogether there is yformed a distribution channel for the gas, forreceiving the gas and distributing it over the length of the slotdischarge opening shortly to be described. Further, the front members rand s are provided with recesses t which, when, the members areassembled, communicate the distribution chambers e, z with the channelsd in the back plate, and the end portions j of the front member elementsr and s are positioned and formed so that the ends f define with thecone-shaped nozzle b of the back plate two passageways disposed one oneither side of the cone-shaped nozzle b, each terminating in anelongated slot g which extends over the length of the line of meltoutlet openings in the cone-shaped nozzle b. Thus, a passageway isprovided -from each of the distribution chambers e, z to the slotdischarge openings g. Also, the ends f of the front member elements formwith the cone-shaped nozzle b a length of passageway adjacent each ofthe slot discharge openings, terminating at the slot discharge openings,which lengths diverge towards the slot discharge openings.

The inserts j are xedly secure in the 'front member elements r and s andserve as baflies to direct gas flow from the distribution chambers e, zinto the channels d.

Thus, the spinning head is constructed so that there are directionalchanges along the flow path from the distribution chambers to the slotdischarge openings. Furi ther, the cross-section, i.e. thecross-sectional flow area, of the path from the distribution chambers e,z to the slot discharge openings g, chan-ges. These constructionfeatures serve to reduce the turbulence of the gas stream issuing fromthe Slots g.

Also, on the distribution chamber side of the diverging lengths u,restrictions are disposed in the path of the gas. Thus, `the lip h ineach of the lfront member elements provides a restriction or oriiice inthe flow path of the gas, and, further, the insert j is positioned in amanner such that restriction k is provided. This construction causes theturbulence of gas issued from the melt outlet openings g to be low.

The number of melt outlet openings can be -300; more or less can also beused. The distribution channels can extend into the front and backmembers a distance of about 7-35 mm., and the width of the channel e canbe about l0 mm. The distribution chambers are disposed parallel to theslot discharge openings g, and the flow path from one distributionchamber e, z to its slot discharge opening g is the same as the flowpath from the other distribution chamber e, z to its discharge slot g,so that flow conditions along the two paths from the distributionchambers will be substantially the same. The width of the slot dischargeopenings g can be 0.3 mm.

As is indicated in FIG. 3, the distribution chambers have connected tothe ends thereof gas inlet conduits o. A gas inlet conduit is connectedto each end of each of the distribution chambers. Desirably these inletconduits are connected to a common source of gas.

Due to the manner in which the spinning head is constructed, gas isdischarged from the slot discharge openings g which is of low turbulenceto the extent that improved results are realized in respect to theproduction of iieeces. In the passage of the gas from the distributionchambers to the slot discharge openings, a continuous change in owvelocity occurs, and a pressure drop occurs, for example a pressure dropof from 0.14 atmospheres gauge to 0.11 atmospheres gauge. This is apressure drop of about 20% and a pressure drop in the amount of about15-3 0% is desirable. In the lengths u of the passageways, theconditions of the gas are substantially the same, and, accordingly, thegases are delivered from the slot discharge openings in about the sameconditions so that improved operation is realized.

As the melt streams issue from the melt outlet openings m, they areengaged by the gas streams, and over a distance of about 5 mm. from theoutlet openings for the melt, the gas streams greatly extend thefilaments. For exam-ple, for an outlet opening size of 400 microns, themelt streams can be drawn into filaments of 1 micron diameter and thisextension takes place substantially within the distance of 5 mm. Thisgreat elongation effects a desired molecular orientation for thefilaments, and is done without substantial breakage of the filaments.

The invention further provides a guide passageway s (see FIG. 3) for thefilaments. The guide passageway is open at both ends and is disposed inspaced relation with respect to the melt outlet openings m. It receivesthe filaments from the outlet openings and also receives the gas fromthe slot discharge openings g, and the guide passageway guides thefilaments on their way to the form (not shown) on which they arecollected for the making of the fabric. The guide passageway can bespaced 3-8 cm., preferably about 5 cm.from the melt outlet openings m.For a length of 320V mm. for the cone-shaped nozzle b, the length of theslot discharge openings g can be about 340 mm., and the length of theinlet opening of the guide passageway s can be about 360 mm. Preferablythese elements are related in this manner, i.e. the length of thecone-shaped nozzle b is less than the length of the gas slot dischargeopenings, and the corresponding dimension of the guide passageway isgreater than the length of the slots. The width of the inlet opening tothe guide channel s' can be about 3 cm. The length of the guide channelis such that the elongation of the filaments is complete before thefilaments leave the guide passageway. As indicated previously, by farthe greater part of the expansion occurs immediately following issuanceof the melt streams from the melt outlet openings m, but some furtherelongation occurs. The filaments become set during the course of travelthrough the guide passageway. For example, for polycaprolactam, the4length of the guide passageway can be 40 om.

As is indicated by the arrows r (FIG. 3) some gas is aspirated from thevicinity of the spinning head into the guide passageway, by reason ofthe movement of the gas streams from the slot discharge openings g. Dueto the fact that these gas streams are at the same conditions, uniformaspiration occurs, so that the aspiration effect does not cause harmfulturbulence.

The amount of gas which is aspirated into the inlet opening p of theguide passageway s will depend on the conditions, and particularly onthe condition of the gas streams issuing from the slot dischargeopenings g. The aspirated air, which can be called second-ary air, canexceed in amount the gas streams from the slot discharge openings g. Forexample, the secondary air can be ten times the amount of gas from theslot discharge openings. This is an important aspect of the operation ofthe spinning head. The secondary gas stream may contribute to thecooling of the melt streams and/or may serve to facilitate evaporationof solvent from the melt streams, whereby the solidification of thethreads is effected. Further, the secondary gas streams may facilitatethe obtaining of a desired water 'content for the fibers. Thus, thesecondary stream may assist the adiabatic cooling of the gas streamsfrom the slot discharge openings so that the desired take-up of water bythe fibers is obtained. On the other hand, the secondary gas stream maybe used to remove excess moisture from the fibers. Also, of course, thesecondary gas streams aid in the setting of the filaments at the desiredmolecular orientation, and aid in the guiding of the filaments on theircourse through the guide passageway.

It will be appreciated that the guide passageway s performs theimportant function of maintaining the individual filaments substantiallyout of contact with each other during the setting thereof. After leavingthe guide passageway s the filaments are collected as a non-woven fieeceon suitable forms. Substantial contacting of the different filamentsdoes not occur until just shortly before the filaments are collected onthe form. This is an important characteristic of the device of theinvention, since, by reason of such operation, it is possible to obtainfieeces of good uniformity.

A plurality of spinning heads according to the invention can be usedtogether, and in such operation each spinning head is provided with itsown guide channel. Further, the guide channel or channels can be rockedto provide a desired shifting of the fibers so that good intermixing ofthe fibers in the non-woven fleece is obtained. Where several spinningheads are used, different melt compositions can be discharged from thevarious heads to produce fieeces of mixed composition.

The spinning head of the invention is Well suited for the spinning ofpolymer compositions in general. It can be used for spinning offilaments of polyamides, polyesters, polyolefins, polyurethanes, etc.The melt can be a solution, and the melt can contain softeners and othermodifying agents. The device can also be used for production of rayonfabrics, particularly when using a collecting form suitable for rayon,such as, for example, that illustrated in FIG. 14 or FIG. 13 of theabove-mentioned co-pending application, Serial No. 341,489, filedJanuary 27, 1964.

The spinning head is well suited for use of steam as the gas utilized todraw the filaments. Water vapor-air mixtures can mso be used. 'The useof water vapor or steam offers the possibility of controlling themoisture content of the filaments. As is indicated above, the use ofsteam or water vapor-air mixture as the gas stream can be correlatedwith the secondary air stream which is aspirated into the guidepassageway s in a manner as will permit close and accurate control ofthe moisture content of the filaments.

The spinning head of the invention provides the further advantage thatthe air streams supplied are at substantially uniform conditions acrossthe entire cross-sectional flow area. Thus, the gas on each side of thefilaments is at the same condition, while at the same time theconditions of the gas along the width of the filaments is the same.

EXAMPLE Polycaprolactam (nylon 6) was spun with a spinning nozzleaccording to the invention, under the followlng conditions:

Melt outlet openings, number Melt outlet diameter microns 400 Meltoutlet spacing, center to center mm 2 Slot discharge opening, length mm340 Slot discharge opening, width mm 0.3 Nozzle temperature C-.. 225 Gasmixture, air:watervapor 10:1 Gas temperature in slots C 225 Gas quantityNm3/min-- 1.5 Guide passageway inlet opening, length mm 380 Guidepassageway inlet, width mm 30 Guide passageway length mm-- 600 Fibertiter den-- 1 While the invention has been described with respect toparticular embodiments thereof, it will be understood that theseembodiments are merely representative of the invention and do not serveto provide the limits thereof.

What is claimed is:

1. In an apparatus for spinning a plurality of filaments which apparatuscomprises at least one elongated spinneret having a plurality ofsubstantially coplanar spinning orifices therein; a pair of fiuid outletslit means on either side of said spinning orifices; means to feedpolymer to said spinning orifices; and means to feed a fluid to each ofsaid slit means; the improvement which comprises said fiuid feedingmeans comprising a first channel means operatively connected to saidslit means via conduit means; a second channel means operativelyconnected to said first channel means via conduit means; and means forfeeding said fiuid to said second channel means whereby fiuid emittedfrom said slit means is at substantially the same velocity atsubstantially all points therealong.

2. The improved apparatus claimed in claim l wherein said channels aresubstantially parallel.

3. The improved apparatus claimed in claim 2 wherein said slit means issubstantially parallel to said first channel.

4. The improved apparatus claimed in claim 1l, including a multiplicityof conduit means between said first and second channels.

5. The improved apparatus claimed in claim 1, including at least oneturbulence-reducing insert in said conduit means.

6. The improved apparatus claimed in claim 1, including means, at bothends of said second channel, for introducing said fiuid thereinto.

7. In the process of producing drawn filaments which comprises issuingpolymer in filament form from a row of substantially coplanar spinningorifices, impinging a fiuid onto both sides of said row of filaments ata velocity higher than the filament velocity, and drawing said filamentswith said fiuid; the improvement which comprises passing said fluidthrough multiple successive channel means connected to each otherthrough conduit means prior to impingement thereof onto said filamentswhich passage substantially reduces the turbulence of said fiuid andmakes the velocity of said fiuid substantially uniform upon impingement.

References Cited UNITED STATES PATENTS 2,411,660 11/1946 Manning 264-17610/1951 Ladisch 264-176 Anderson et al 264-168 Detzsch et a1. 264-168Stevens 264-167 Buschmann et a1. 264-176 Vinicki 264-176 Oberly 264-210Bauer 264-207 DONALD I. ARNOLD, Primary Examiner.

